When you first create a group on Count.It your group is registered on our free BASIC plan. Under the BASIC plan, you can invite as many people to join as you like, and always keep track of your group's basic activity. That being said, for BASIC groups, the Count.It Slack integration limits the group to only reflect the top 15 ranked members listed on the leaderboard.
We strongly suggest that if you are looking to create a group of 15+ members that you take a look at the features offered on Count.It PRO. We find groups of that size or larger operate more effectively and have more success when given the options of tracked activities, bonus points & manual entries, internal teams, rewards, etc.